How to use static_cast to convert a template matrix class of int type to double type in operator overloading?

Writing an operator function to multiply a custom template matrix class with a scalar.

template <typename T>
class Matrix {
public:
  Matrix() //default constructor
  Matrix(size_t Row, size_t Col); //initialize with zeros of row,col 
  explicit Matrix(const vector<vector<T>> matElems); // create a matrix from vec<vec>>
  friend Matrix<ret_type> operator*(const Matrix<mat_type> matrix,
                                    const scalar_type scalar);
private:
  vector<vector<T>> elements;
  std::size_t nRows;
  std::size_t nCols;
};

template <typename mat_type, typename scalar_type,
          typename ret_type = decltype(mat_type() * scalar_type())>
Matrix<ret_type> operator*(const Matrix<mat_type> matrix,
                           const scalar_type scalar) {

  Matrix<mat_type> copy_matrix = matrix;

  Matrix<ret_type> result = static_cast<Matrix<ret_type>>(copy_matrix);

  for (vector<ret_type> v : result.elements) {
    std::transform(v.begin(), v.end(), v.begin(),
                   std::bind1st(std::multiplies<ret_type>(), scalar));
  }

  return result;
}

Error: no matching function for call to ‘Matrix::Matrix(Matrix&)’ on the line Matrix<ret_type> result = static_cast<Matrix<ret_type>>(copy_matrix)

Reason of doing this is to cast an int type matrix to double if it is multiplied by a double scalar.